it's little things like roads not connected at all.
or someone has tried to add a road, made a mess of it, and just walked away.
i know that there was discussion on how "you shouldn't delete someone else's work", but if i come across a random bit of road that's clearly out of place (like a 2M road on top of a hospital roof), i just delete it.
i try as much as to preserve the road if it's a little out of place, and just edit it till it fits.
i'm happy to take on more work (gives me something to do) but i need to be able to move up the ranks.